Port 2000

The Cisco Skinny Client Control Protocol (SCCP) is designed primarily for communication between Cisco IP phones and Cisco Unified Communications Managers (CUCM). Originally created by Selsius Corporation, SCCP was later acquired and further developed by Cisco, serving as the backbone signaling protocol in many Cisco call-processing environments. It enables lightweight communication by offloading much of the call control intelligence to CUCM, making IP phones simpler and more cost-effective.

SCCP messages are transmitted over TCP (and optionally UDP) port 2000, using a simple and efficient binary message format. The protocol supports functions such as registration, call signaling, feature negotiation, phone configuration updates, and media stream control. Because it is lightweight compared to other protocols like SIP or H.323, it is well-suited for environments with numerous endpoints.

While SCCP is proprietary and mostly limited to Cisco devices, it remains widely used within Cisco-dominated enterprise telephony networks. The protocol facilitates integration with Cisco's extensive suite of IP-based communication solutions, enabling features such as call forwarding, conferencing, voicemail access, and directory services.